Implement all core features: Knowledge pipeline, RAG chat, Todos, Habits, Study Cards, Tags, Dashboard

- Google OAuth authentication with callback flow
- Knowledge ingest pipeline (TEXT/WEB/YOUTUBE → chunking → categorization → embedding)
- OCI GenAI integration (chat, embeddings) with multi-model support
- Semantic search via Oracle VECTOR_DISTANCE
- RAG-based AI chat with source attribution
- Todos with subtasks, filters, and priority levels
- Habits with daily check-in, streak tracking, and color customization
- Study Cards with SM-2 spaced repetition and LLM auto-generation
- Tags system with knowledge item mapping
- Dashboard with live data from all modules

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

sundol-backend/pom.xml

@@ -56,10 +56,12 @@
         <dependency>
             <groupId>com.oracle.database.security</groupId>
             <artifactId>osdt_cert</artifactId>
+            <version>21.18.0.0</version>
         </dependency>
         <dependency>
             <groupId>com.oracle.database.security</groupId>
             <artifactId>osdt_core</artifactId>
+            <version>21.18.0.0</version>
         </dependency>
 
         <!-- JWT -->
@@ -81,6 +83,13 @@
             <scope>runtime</scope>
         </dependency>
 
+        <!-- Google Auth Library -->
+        <dependency>
+            <groupId>com.google.auth</groupId>
+            <artifactId>google-auth-library-oauth2-http</artifactId>
+            <version>1.30.1</version>
+        </dependency>
+
         <!-- Lombok -->
         <dependency>
             <groupId>org.projectlombok</groupId>